The CBL1/9-CIPK1 calcium sensor negatively regulates drought stress by phosphorylating the PYLs ABA receptor

The stress hormone, Abscisic acid (ABA), is crucial for plants to respond to changes in their environment. It triggers changes in cytoplasmic Ca2+ levels, which activate plant responses to external stresses. However, how Ca2+ sensing and signaling feeds back into ABA signaling is not well understood. Here we reveal a calcium sensing module that negatively regulates drought stress via modulating ABA receptor PYLs. Mutants cbl1/9 and cipk1 exhibit hypersensitivity to ABA and drought resilience. Furthermore, CIPK1 is shown to interact with and phosphorylate 7 of 14 ABA receptors at the evolutionarily conserved site corresponding to PYL4 Ser129, thereby suppressing their activities and promoting PP2C activities under normal conditions. Under drought stress, ABA impedes PYLs phosphorylation by CIPK1 to respond to ABA signaling and survive in unfavorable environment. These findings provide insights into a previously unknown negative regulatory mechanism of the ABA signaling pathway, which is mediated by CBL1/9-CIPK1-PYLs, resulting in plants that are more sensitive to drought stress. This discovery expands our knowledge about the interplay between Ca2+ signaling and ABA signaling.

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was used to to collect stomatal aperture data .Leaf temperature was measured using FLIR ResearchIR Max professional software.Confocal images were captured by by the Olympus IX83-FV3000confocal microscope.LUC signals were captured by by Lumazone Pylon 2048B.The absorbance was measured using a BioTek microplate spectrophotometer.The phosphorylation signals were detected with a Typhoon 9410 imager.Protein sequences were collected in in NCBI.Quantification and statistical analyses were performed using Fiji (Image J), and Graph Pad Prism 9.0.Bar charts and plot boxes were generated by by GraphPad Prism.Adobe Photoshop CC CC 2018 and Adobe Illustrator were used for image assembly.Protein sequences were aligned with Jalview software.Amino acid conservativeness analysis was performed using the MEME online tool. of of concern Policy information about dual use research of of concern Hazards Could the accidental, deliberate or or reckless misuse of of agents or or technologies generated in in the work, or or the application of of information presented in in the manuscript, pose a threat to: Does the work involve any of of these experiments of of concern: No No Yes Demonstrate how to to render a vaccine ineffective Confer resistance to to therapeutically useful antibiotics or or antiviral agents Enhance the virulence of of a pathogen or or render a nonpathogen virulent Increase transmissibility of of a pathogen Alter the host range of of a pathogen Enable evasion of of diagnostic/detection modalities Enable the weaponization of of a biological agent or or toxin Any other potentially harmful combination of of experiments and agents nti-GST Mouse Monoclonal Antibody: TransGene, HT601; Anti-His Mouse Monoclonal Antibody: TransGene, HT501; Anti-FLAG Antibody: 1:5000, TransGene, HT201; Anti-GFP Mouse Monoclonal Antibody: 1:5000, TransGene, HT801; Anti--Tubulin Mouse Monoclonal Antibody: 1:5000, TransGene, HC101; Goat Anti-Mouse IgG (H+L), HRP Conjugate: 1:5000, TransGene, HS201; Phosphoserine Monoclonal Antibody, 1: 1: 2000, Immunoway, YM3440.